Automated systems often make calls to customers to provide general announcements for some event, to broadcast a promotional campaign, to provide billing information, etc. If a customer answers the call, then the automated system may provide an interactive message that permits the customer to listen to the message, to select various options to receive additional information, to place an order for goods or services, to review account information, etc. If, however, a machine answers the call, such as an answering machine, a facsimile machine, etc., then it is desirable that the network be able to detect that the call was answered by the machine so that a non-interactive message or customized message can be delivered (e.g., in the form of a voicemail message), a fax can be sent, or some other operation can be performed. Unfortunately, existing automated systems, that send and receive calls using a voice over Internet protocol (VOIP), cannot detect whether a human or a machine answers the call.